1. Field of the Invention
The present invention relates to a jacket for preventing ink from adhering to an impression cylinder or a transport cylinder of a printing press, the jacket being wound around and installed on, the impression cylinder or the transport cylinder.
2. Description of the Related Art
An example of a printing press which makes prints on both surfaces of a sheet of paper or the like is shown in FIG. 5. This printing press is a sheet-fed rotary printing press for making prints on both sides of paper. The printing press is configured of a sheet feeder 101, a printing unit 102, and a paper delivery unit 103. Sheets of paper stacked in the sheet feeder 101 are removed therefrom sheet-by-sheet. The sheets are then supplied to the printing unit 102 by the support of a register board 104, a swing gripper 105, and a transport cylinder 106.
The printing unit 102 is configured of four front side printing units 107A, 107B, 107C, and 107D, and four back side printing units 108A, 108B, 108C, and 108D. The front side printing units 107A to 107D are provided for first to fourth colors, respectively. Each of the front side printing units 107A to 107D is configured of a blanket cylinder (a rubber cylinder) 110a, a plate cylinder 111a, and an inking device (not shown), which are provided on each of upper portions of impression cylinders 109a. Each of the upper portions of the impression cylinders 109a includes a sheet gripper. Likewise, the back side printing units 108A to 108D are provided for the first to fourth colors, respectively. Each of the back side printing units is configured of a blanket cylinder (a rubber cylinder) 110b, a plate cylinder 111b, and an inking device (not shown), which are provided on each of lower portions of impression cylinders 109b. Each of the lower portions of the impression cylinders 109b includes a sheet gripper.
The front side printing units 107A to 107D and the back side printing units 108A to 108D are sequentially connected with one another in the following manner. The front side printing unit 107A of the first color is positioned first to make a print, and the back side printing unit 108A of the first color is positioned next to the front side printing unit 107A, and then, the front side printing unit 107B of the second color is positioned next to the back side printing unit 108B.
A sheet of paper fed from the sheet feeder 101 is transferred to the impression cylinder 109a of the first front side printing unit 107A. The transferred sheet is then pressed by the impression cylinder 109a toward the blanket cylinder 110a, and thus a print of the first color is made on the front side of the sheet. Subsequently, the sheet of paper is transferred to the impression cylinder 109b of the first back side printing unit 108A. The sheet is then pressed by the impression cylinder 11a toward the blanket cylinder 110b and thus a print of the first color is made on the back side of the sheet. Thereafter, as in the aforementioned manner, prints of the second to fourth colors are alternately made on the front and back sides of the sheet of paper by the second to fourth front side printing units 107B to 107D, and the second to fourth back side printing units 108B to 108D. After the prints are completed, the sheet of paper is transferred from the impression cylinder 109b, which is of the last unit, to a transport cylinder 112 and then is discharged from the paper delivery unit 103. Such a printing press for making prints on both sides of a sheet of paper is disclosed in Japanese Unexamined Patent Application Publication No. 11-105249, for example.
In such a printing press for making two-sided prints, the impression cylinders other than the impression cylinder 109a located at the most upstream in the operation, press the printed surfaces. Specifically, the surfaces where the ink is attached are pressed to the blanket cylinders 110a, and 110b. The ink thus adheres to the impression cylinders 109a and 109b. Accordingly, the ink adhering to the impression cylinders 109a and 109b adheres onto a printed material (the sheet of paper) to be processed thereafter. The attached ink on the printed material causes smearing on the printed material, and leads to a concern that the smearing on the printed material makes the printed material a failure.
In FIG. 6, an aspect of how the ink adheres to the printed material is schematically shown. The front side of a sheet of paper 113 is pressed by the impression cylinder 109a toward the blanket cylinder 110a of the first front side printing unit 107A. A piece of ink 114a is then placed on the front side of the sheet of paper 113, that is, a print is made. Next, in the first back side printing unit 108A, the back side of the sheet of paper 113 is pressed by the impression cylinder 109b toward the blanket cylinder 110b. A piece of ink 114b is then placed on the back side of the sheet of paper 113. At this time, the piece of ink 114a placed on the front side of the sheet of paper 113, is transferred to the impression cylinder 109b. Subsequently, the transferred ink moves to a sheet of paper which comes next. As a result, the printed material is smeared. It should be noted that the occurrence of such a problem is not limited in printing presses making prints on both sides of paper. The problem also occurs in a case where a print is made on the back side of a sheet of paper by reversing the front side of the sheet of paper after a print on the front side of the sheet of paper is made in a printing press having a function of sequentially making prints on both sides of paper. Furthermore, a similar problem also occurs with the transport cylinder 112, although the extent of the problem is not as much as with the impression cylinder 109b which presses the sheet of paper 113 toward the blanket cylinder 109b. This is because the transport cylinder 112 transports the sheet of paper 113 in a state where the printed surface of the sheet of paper 113 faces the front surface of the cylinder. Incidentally, such a transport cylinder described above includes intermediate cylinders 110 shown in FIG. 2 of Japanese Unexamined Patent Application Publication No. 11-105249 which is mentioned above. The above described transport cylinder also includes intermediate cylinders and transfer cylinders which transport a sheet of paper between each of impression cylinders of a printing unit in a single-side printing press.
In order to prevent such smearing on printed materials, as shown in FIG. 7, the following technique has been considered. Jackets 120 resistant to the adhesion of ink are installed onto the impression cylinders 109a positioned to make prints after the second front side printing unit 107B, the impression cylinders 109b of all the back sides printing units 108A to 108D, and the front surface of the transport cylinder 112, respectively, has been considered (Japanese Unexamined Patent Application Publication No. 2003-335075). The jacket disclosed in Japanese Unexamined Patent Application Publication No. 2003-335075 is formed in the following manner. A ceramic thermal sprayed layer 122 is formed on a base member 121 by means of thermal spray. Sequentially, a coating of a low surface energy resin 123, which is a silicone-based resin, is made thereon. Reference numeral 124 denotes holes formed in the ceramic thermal sprayed layer 122.
As shown in FIG. 8, the jacket 120 disclosed in Japanese Unexamined Patent Application Publication No. 2003-335075 is formed by forming the ceramic thermal sprayed layer 122 by means of the thermal spray on the base member 121. It is, however, not easy to form a ceramic layer having a uniform film thickness, in any way. Moreover, in order to closely attach a ceramic onto the base member 121 made of a metallic plate or the like, it is necessary to provide a metal thermal sprayed layer 125 therebetween. For this reason, the productivity thereof is not good.
Furthermore, the jacket 120 described in Japanese Unexamined Patent Application Publication No. 2003-335075 needs to be frequently replaced with another. This is because the low surface energy resin 123 on the surface of the jacket 120 tends to be separated therefrom and to be worn out. Moreover, since the low surface energy resin 123 is relatively soft, paper dust or other dust easily enters therein. In addition, since the electrostatic property of the low surface energy resin 123 is not good, the low surface energy resin 123 tends to be electrostatically charged. Accordingly, paper dust or other dust is likely adsorbed to the low surface energy resin 123. When ink adheres to the adsorbed paper dust or other dust, ink smearing is generated in a short period of time. It should be noted that since the ceramic thermal sprayed layer is thermally sprayed on the base member 121 made of a metallic plate or the like, there is another problem where the base member 121 having been used once cannot be used again.
The present invention solves the aforementioned problems in the conventional jackets. The present invention provides a jacket for an impression cylinder or a transport cylinder, which jacket makes the impression cylinder or the transport cylinder resistant to the attachment of ink as a matter of course. Furthermore, the present invention provides the jacket with durability as well as a simple manufacturing process, which makes the impression cylinder or the transport cylinder resistant to the attachment of paper dust or the like.